1. Field of the Invention
This invention relates to a suspension device for a hard disc drive apparatus (HDD) used in an information processing apparatus, such as a personal computer.
2. Description of the Related Art
A hard disc drive apparatus (HDD, hereinafter referred to simply as a disc drive apparatus) is used in an information processing apparatus, such as a personal computer. The disc drive includes a magnetic disc that rotates around a spindle, a carriage turnable around a pivot axis, etc. A suspension device is provided on an arm of the carriage.
The suspension device includes a load beam fixed to the carriage, a flexure fixed overlapping the load beam, etc. A slider is attached to a tongue portion that is formed on the flexure. The slider is provided with an element (transducer) for reading or writing data.
Flexures of various forms are being manufactured according to required specifications. A flexure with conductors has been developed as an example flexure. The flexure with conductors includes a metal plate formed of a thin stainless steel plate, a insulating layer formed thereon, a read conductor, a write conductor, etc. The read and write conductors are individually formed on the insulating layer. If necessary, the flexure may be provided with heater conductors.
Respective one ends of the read and write conductors are connected to the read and write elements. For example, MR elements are used as the read and write elements. The respective other ends of the read and write conductors are connected to an amplifier. A pair of heater conductors are connected to a heater that is contained in the slider.
In manufacturing the suspension device, conductor portions and the like of the flexure may possibly be charged with static electricity if they come into contact with their surrounding members with the read and write conductors disconnected from the amplifier. If this static electricity flows through the read and write conductors into the read and write elements, the elements may possibly be destroyed by electrostatic discharge (ESD).
An example of anti-ESD means is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2002-123917. In this prior art, a large number of diodes are connected to the read and write conductors, and voltage produced by frictional charge is spread by the diodes. In a conventional suspension device with this anti-ESD means, the many very small diodes must be connected to the read and write conductors to obtain a predetermined polarity. Thus, bonding the diodes requires much labor and a larger number of components, thereby entailing an increase in cost.
In another example of anti-ESD means, a high-resistance semiconductive layer is used in place of the diodes to cover conductor portions of a flexure. This semiconductive layer is grounded to a metal plate. Thus, static electricity with which the flexure is charged can be released to the metal plate through the semiconductive layer.
However, in a flexure with conductors that is provided with heater conductors, for example, a relatively large potential difference continues to be applied between conductors during use of the suspension device. Thus, migration may occur along the semiconductive layer between the conductors that are subject to the potential difference, so that a short-circuit-causing substance, such as a dendrite, may possibly be formed.